In recent years, the implementation of a technology that will comprehend the intentions and assist the movements of people within spaces such as offices, homes, and public facilities has been anticipated. In order for a technology that monitors people in this manner to be implemented, it is necessary to know where the people are within the space, and the implementation of advanced human detection has become an issue.
Much research has been done on human detection, and various types of methods have been proposed. Human detection methods that use known visible-light cameras include many methods that involve statistical training that uses local features and boosting. Human detection methods have also been proposed that use Histogram of Oriented Gradients (HOG) features, which are features that express gradient directions of brightness as local features in the form of a histogram (for example, refer to Non-Patent Literature 1).